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        검색결과 335

        201.
        2006.09 구독 인증기관·개인회원 무료
        New Al-based alloys with very high ultimate tensile strength were developed in high Al concentration range of 91-95 at.% for Al-Fe-Cr-Ti-M (M: Co and Mo) systems and Al-Fe-Cr-Mo-Ti-Co system by the dispersion of nanoscale quasicrystalline particles in Al phase. The effect of adding elements, M was discussed in the viewpoint of stability of super-cooled liquid state and formation ability of quasicrystalline phase. The P/M Al-Fe-Cr-Ti-M alloys with dispersed nanoscale quasicrystalline particles exhibited ultimate tensile strength of 350MPa at 573K and 200MPa at 673K.
        205.
        2006.04 구독 인증기관·개인회원 무료
        A connection between pulse-periodical laser radiation power and stability of liquid-metal contacts between powder particles during selective laser sintering (SLS) is determined based on analysis solving the problem of stability of liquid column in the gravity and capillary forces field. On the grounds of obtained relationships the optimization of pulse-periodical laser radiation power and SLS-process duration is realized, that allows to produce voluminous powder porous materials with pre-determined physical and mechanical properties and surface geometry. Results of metallographic investigations of powder porous materials of titanium powder produced with technological regimes calculated by means of obtained relationships are given in the work
        206.
        2006.04 구독 인증기관·개인회원 무료
        Correlations between in-flight particle, splat and coating microstructure of thermally sprayed Ni20Cr were investigated. Flame spray and arc spray systems were employed for spraying Ni20Cr powder and Ni20Cr wire, respectively. The results showed that the arc spray process produced a broader size distribution for both in-flight particles and splats compared to flame process. Flower-like splat morphology was obtained from the arc spray whereas a pancake-like splat was obtained by flame spray. Ni20Cr coating sprayed by arc process had a denser microstructure, lower porosity and better adhesion at the interface.
        207.
        2006.04 구독 인증기관·개인회원 무료
        The anatase particle was facetted at the free surface and a neck formation between the anatase particles prior to the phase transformation occured. This resulted in the severe lattice distortion at the region of the interface near the neck and this can act as the nucleation sites for the phase transformation. The grain growth of rutile particles after the phase transformation grew very fast by the sweeping phenomena of grain boundary. Therfore, It leaded to the microstructure without the rutile phase located in anatase particle.
        209.
        2006.04 구독 인증기관·개인회원 무료
        Monosized germanium micro particles are prepared by a newly developed Pulsated Orifice Ejection Method. The obtained particles are categorized into two kinds of the microstructures as refined and coarse ones. The morphological difference is estimated to be determined by the undercooling level during nucleation. Actually, the increase in the temperature of the melt was effective in coarsening the microstructure, because the temperature of the melt intensely relates to the undercooling level. The transition temperature of coarse and refined microstructures is found to be 1300-1350K. Furthermore, a triggered nucleation could improve the crystallinity of the particles in the short separation.
        210.
        2006.04 구독 인증기관·개인회원 무료
        Mono-sized silicon particles were effectively fabricated by a novel way named pulsated orifice ejection method (POEM). The particles are with very narrow particles size distribution and very small standard deviation of mean particle size. There are two different types spherical silicon particles were found. One consists of many grains mainly in random boundaries. The other consists of two or three grains with only twin orientation relationships, even single crystal in cross-section was also found within this type of spherical silicon particles.
        212.
        2006.04 구독 인증기관·개인회원 무료
        Three-dimensional artificial crystals with periodicity corresponding to terahertz wave lengths were fabricated by self-assembling monosized metal spherical particles. The metal crystals were weakly sintered to utilize them as templates. The metal templates were inverted to air spheres crystal embedded in dielectric resin though infiltration and etching. The resulting resin inverted crystals clearly presented the photonic stop gaps within terahertz wave region and the frequencies of the gaps were confirmed to agree well with calculation by plane wave expansion method.
        213.
        2006.04 구독 인증기관·개인회원 무료
        Ultrafine Au-Pb particles prepared by two method, (1) simultaneous evaporation of Au and Pb in inert gas and (2) subsequent vapor condensation of Pb in a differentially evacuated tube onto flying Au nanoparticles prepared by gasevaporation technique, were observed by electron microscopy. In the method (1), the particles that grew at the region where the two smoke masses converged, consisted of alloy phases. In the method (2), the particles consisted of two or three phases of Au, , and Pb phases in turn from the inner part, Pb-rich particles being composed of only two phases of and Pb.
        215.
        2005.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 재활용 PET-Bottle-Particles(PBT)가 함유된 4가지 생육배지를 이용하여 플러그묘 재배의 가능성을 실험하기 위해 유리온실에서 수행되었다. 토마토 '서광'의 플러그묘를 PBT 100%, peat moss 100%, 그리고 PBT 50%+peat moss 50%가 함유된 배지 및 상업적으로 이용되는 배지(토실이)를 대조구로 이용하여 육묘하였다. 128공 플러그 트레이에서 2004년 7월 12일에 파종하여 플러그묘의 생육은 파종 후 30일째 측정하였다. 모든 처리에서 95% 이상 발아하였다. 초장, 지상부 생체중과 건물중, 엽면적, 그리고 하배축 길이는 대조구에서 가장 컸다. 뿌리 길이와 무게는 PBT 100%처리에서 가장 컸으며, 이 배지의 pH는 7.3이었다. PBT 50%+peat moss 50%처리에서 엽면적과, 지상부 건물중이 PBT 100% 처리에서 보다 컸으며, peat moss 100%처리에서 가장 작았다. PBT를 사용함으로 인한 독성증상은 관찰되지 않았다. 이 결과는 원예 묘종 생산에 있어 배지의 물리성 개선을 위한 구성요소로써 재활용 가능한 PBT의 이용 가능성을 제시해 준다.
        4,000원
        216.
        2005.12 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        The ultra-fine particles emitted by automobile are emerging issue because it is known to have adverse human health effect. Particles emitted from automobile and other engines are a complex mixture of elementary and organic carbons and other chemicals. Especially diesel particles are mainly composed of elemental carbon (soot) and volatile compounds derived from unburned and partially burned fuel, and lubricating oil and sulfate. More than 90% of particle number is usually in the ultra-fine particle size range. Ultra-fine particles are known to have increased ability to cause pulmonary inflammation. Adverse health effect may be explained by the greater surface area of the ultra-fine material, which delivered oxidative stress because of a greater surface for the generation of free radicals by as yet unknown mechanisms, or for release of redox-active transition metals and organics. In conclusion, over the past decade attention has been paid on physical/chemical characteristic, mechanism, toxicity, health effects, however, we do not have enough information about ultra-fine particles. So we need to conduct continuous research and management on ultra-fine particles.
        4,000원
        217.
        2005.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Copper is able to work as a current collector under wide range of hydrocarbon fuels without coking in Solid oxide fuel cells (SOFCs). The application of copper in SOFC is limited due to its low melting point, which result in coarsening the copper particle. This work focuses on the sintering of copper powder with ceria coating layer. Ceria-coated powder was prepared by thermal decomposition of urea in solution, which containing CuO core particles. The ceria-coated powder was characterized by XRD, ICP, and SEM. The thermal stability of the ceria-coated copper in fuel atmosphere was observed by SEM. It was found that the ceria coating layer could effectively hinder the grain growth of the copper particles
        4,000원